Flicking in games?

[DarkStar02]

In Unreal Tournament 2004, my guns have artifacts (more like flashing black textures). It was playable, so I never really let it bother me. Then I moved on to Oblivion. This game is 100% unplayable. Artifacts everywhere. Then, when I play call of Duty 2, everything is fine. What's going on here?

Stuff I've already tried (for Oblivion): V-Sync On, Temporal-AA disabled, settings at lowest, underclocking, overclocking, video card bios flashing, pipeline unlocking. Nothing seems to be working. Can someone give me a hand here?

EDIT:
Also tried: Updating mobo bios, installing newest Omega drivers, reverting to older drivers

EDIT2:
Motherboard: DFI LanpartyUT nF4 Ultra-D
Processor: AMD Opteron 170 CCBWE 0543 TPMW @ 2.55
RAM: Mushkin 1024 [512x2] Dual Channel PC3200 DDR SDRAM (2.5-3-3-8 @ 200 MHz)
Video Card: Borrowed X800 GTO2 Limited Edition (Reverted to stock from X850XT PE speeds)
HDD: 36.7 GB 10,000 RPM Maxtor Raptor drive // 11 GB 5,400 RPM Maxtor drive
PSU: Thermaltake TR2 470W PSU v2.0
Optical Drives: NEC DVD-RW Combo Drive // CD-RW Combo Drive // DVD-ROM // CD ROM // Floppy
Mouse+Keyboard: Wireless IntelliMouse explorer 2.0 // Microsoft Wireless Desktop Elite Keyboard // Flexiglow FX GamePad with Blue LEDs.
Sound: Onboard sound // 4 Speakers + Sub Woofer + 2 Speaker Stereo input/output // Plantronics DSP500 Gaming Headset
Monitor: Dell E172FP 17" LCD
Benchmarks: Unknown

EDIT 3: It also puts my max settings at decent settings but resolution at 640x320 or something like that.

 

[ITSTHINKING]

Hmm how long have youhad the card for? I'd try an rma

 

[DarkStar02]

I bought it refurbished from Newegg over 2 months ago but it's only been in my system for about 2 weeks.